WESPs have been used for many years to remove dust, acid mist and other particulates from water-saturated air and other gases by electrostatic means. In a WESP, particulate and mist laden gas flows between discharge and collecting electrodes, where the particulate and mist are charged by a high intensity corona emitted from the high voltage discharge electrodes. As the gas flows further within the WESP, the charged particulate matter and mist is electrostatically attracted to grounded collecting plates or electrodes, where it is collected. The collected materials are washed off by an irrigation film of water.
The design of the WESP utilizes negatively charged high voltage discharge electrodes separated from the grounded collecting electrodes by porcelain or ceramic insulators. The insulators are mounted external to the process gas stream. This type of system is used to remove pollutants from various industrial gas streams, such as chemical incinerators, coke ovens, ceramic brick furnaces, coal fired power plants, multi-fuelled power plant, food drying plants, non-ferrous metallurgical plants and petrochemical plants.
In certain industries, such as the petrochemical industry, a WESP is required to be operating for long periods of time, generally up to 60 months, and cannot be shut down for maintenance. This extended period of operation raises problems with overall maintenance, but especially insulator maintenance.